Don't use a worker for downloading projects

We are not doing anything else on the main thread that would
justify spinning up a Worker. They are just another source of
possible error.

package.json

@@ -47,7 +47,6 @@
     "@turbowarp/scratch-svg-renderer": "^1.0.0-202401111326-62c0f26",
     "babel-jest": "^27.4.5",
     "babel-loader": "^8.2.3",
-    "comlink": "^4.3.1",
     "copy-webpack-plugin": "^6.4.1",
     "cross-env": "^7.0.3",
     "css-loader": "^5.2.7",

src/packager/download-project.js

@@ -70,10 +70,12 @@ const mutateScratch3InPlace = (projectData) => {
   optimizeSb3Json(projectData);
 };
 
-export const downloadProject = async (projectData, progressCallback = () => {}) => {
+export const downloadProject = async (projectData, progressCallback = () => {}, signal) => {
   let analysis = unknownAnalysis();
 
   const options = {
+    signal,
+
     onProgress(type, loaded, total) {
       progressCallback(type, loaded, total);
     },

src/packager/load-project.js

@@ -1,30 +1,26 @@
-import {transfer, proxy} from 'comlink';
-import createDownloadWorker from '../build/p4-worker-loader!./download-project';
 import {readAsArrayBuffer} from '../common/readers';
 import request from '../common/request';
 import {AbortError} from '../common/errors';
 
 const downloadProject = async (buffer, progressCallback) => {
-  const {worker, terminate} = await createDownloadWorker();
-  let terminateAndReject;
-  const downloadPromise = new Promise((resolve, reject) => {
-    worker.downloadProject(transfer(buffer, [buffer]), proxy(progressCallback))
-      .then((res) => {
-        terminate();
-        resolve(res);
-      })
-      .catch((err) => {
-        terminate();
-        reject(err)
-      });
-    terminateAndReject = () => {
-      terminate();
-      reject(new AbortError());
-    };
-  });
+  const controller = typeof AbortController === 'function' && new AbortController();
+  const downloadProject = await import(/* webpackChunkName: "downloader" */ './download-project.js');
+  let reject;
   return {
-    promise: downloadPromise,
-    terminate: terminateAndReject
+    promise: new Promise((_resolve, _reject) => {
+      reject = _reject;
+
+      downloadProject.downloadProject(buffer, progressCallback, controller && controller.signal)
+        .then(result => _resolve(result))
+        .catch(err => _reject(err));
+    }),
+
+    terminate: () => {
+      reject(new AbortError());
+      if (controller) {
+        controller.abort();
+      }
+    }
   };
 };